docs: def convert_hpdist(self, node):
          """
          Convert the given node into a probability mass function for the
          hypo depth distribution.
  
          :param node: a hypoDepthDist node
          :returns: a :class:`openquake.hazardlib.pmf.PMF` instance
          """
          with context(self.fname, node):
              hcdist = [(hd['probability'], hd['depth'])
                        for hd in node.hypoDepthDist]
              if not self.spinning_floating:  # consider the first hypocenter
                  hcdist = [(1, hcdist[0][1])]
              return pmf.PMF(hcdist)